Shear-induced vorticity aligned flocs in a temperature responsive colloid-polymer mixture
Shear-induced vorticity aligned flocs in a temperature responsive colloid-polymer mixture
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DOI：
10.3389/fphy.2022.955006
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发表时间：
2022-09
期刊：
影响因子：
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通讯作者：
Ryle Rel;D. Terwilliger;R. McGorty
中科院分区：
文献类型：
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作者：
Ryle Rel;D. Terwilliger;R. McGorty
在许多软物质系统中都能看到剪切驱动的图案化现象。我们利用流变学和光学显微镜来探究当我们剪切一种含有温度敏感微凝胶颗粒的胶体 - 聚合物混合物时所形成的结构。通过升高温度，我们可以增强颗粒间的吸引力，并从类液体行为转变为类凝胶行为。并且随着温度以及系统状态的改变对样品施加剪切流，我们能够影响介观胶体团簇的形态。我们可以制备由纤维状、拉长的胶体密集团簇组成的凝胶，或者形成更各向同性的团簇。对具有不同团簇形态的胶体 - 聚合物系统进行了流变学测量，并观察到了剪切诱导的絮凝现象。在剪切速率足够高以产生拉长的团簇，但又足够低以至于不会使团簇破裂的情况下，我们观察到与涡度方向对齐且在流变仪的平行板之间滚动的对数状絮凝物。
Shear driven patterning is seen in many soft matter systems. We use rheology and optical microscopy to probe the structures formed when we shear a colloid-polymer mixture containing temperature-sensitive microgel particles. By increasing the temperature, we can increase the particle attraction and transition from liquid-like to gel-like behavior. And by applying shear flow to the sample as the temperature and, hence, state of the system changes, we can affect the morphology of mesoscopic colloidal clusters. We can produce gels comprised of fibrous, elongated colloid-dense clusters, or we can form more isotropic clusters. The rheology is measured and shear-induced flocculation observed for colloid-polymer systems with different cluster morphologies. At shear rates high enough to produce elongated clusters but low enough to not break clusters apart, we observe log-like flocs that are aligned with the vorticity direction and roll between the parallel plates of our rheometer.